// vim:ts=4:sw=4:noet

/**
 * An autosuggest textbox control.
 * @class
 * @scope public
 */
function AutoSuggestControl(oTextbox /*:HTMLInputElement*/, 
							oProvider /*:SuggestionProvider*/) {
	
	/**
	 * The currently selected suggestions.
	 * @scope private
	 */   
	this.cur /*:int*/ = -1;

	/**
	 * The dropdown list layer.
	 * @scope private
	 */
	this.layer = null;
	
	/**
	 * Suggestion provider for the autosuggest feature.
	 * @scope private.
	 */
	this.provider /*:SuggestionProvider*/ = oProvider;
	
	/**
	 * The textbox to capture.
	 * @scope private
	 */
	this.textbox /*:HTMLInputElement*/ = oTextbox;
	
	/**
	 * Timeout ID for fast typers.
	 * @scope private
	 */
	this.timeoutId /*:int*/ = null;

	/**
	 * The text that the user typed.
	 * @scope private
	 */
	this.userText /*:String*/ = oTextbox.value;

	//initialize the control
	this.init();
	
}

/**
 * Autosuggests one or more suggestions for what the user has typed.
 * If no suggestions are passed in, then no autosuggest occurs.
 * @scope private
 * @param aSuggestions An array of suggestion strings.
 * @param bTypeAhead If the control should provide a type ahead suggestion.
 */
AutoSuggestControl.prototype.autosuggest = function (aSuggestions /*:Array*/,
													 bTypeAhead /*:boolean*/) {
	
	//re-initialize pointer to current suggestion
	this.cur = -1;
	
	//make sure there's at least one suggestion
	if (aSuggestions.length > 0) {
		if (bTypeAhead) {
		   this.typeAhead(aSuggestions[0]);
		}
		
		this.showSuggestions(aSuggestions);
	} else {
		this.hideSuggestions();
	}
};

/**
 * Creates the dropdown layer to display multiple suggestions.
 * @scope private
 */
AutoSuggestControl.prototype.createDropDown = function () {
	//create the layer and assign styles
	this.layer = document.createElement("div");
	this.layer.className = "suggestions";
	this.layer.style.position = "absolute";
	this.layer.style.visibility = "hidden";
	this.layer.style.width = this.textbox.offsetWidth - 2 + 'px';
	this.layer.style.zIndex = 2000;
	document.body.appendChild(this.layer);
	
	//when the user clicks on the a suggestion, get the text (innerHTML)
	//and place it into a textbox
	var oThis = this;
	this.layer.onmousedown = 
	this.layer.onmouseup = 
	this.layer.onmouseover = function (oEvent) {
		oEvent = oEvent || window.event;
		oTarget = oEvent.target || oEvent.srcElement;

		if (oEvent.type == "mousedown") {
			oThis.textbox.value = oTarget.firstChild.nodeValue;
			oThis.hideSuggestions();
		} else if (oEvent.type == "mouseover") {
			oThis.highlightSuggestion(oTarget);
		} else {
			oThis.textbox.focus();
		}
	};
};

/**
 * Gets the left coordinate of the textbox.
 * @scope private
 * @return The left coordinate of the textbox in pixels.
 */
AutoSuggestControl.prototype.getLeft = function () /*:int*/ {
	var oNode = this.textbox;
	var iLeft = 0;
	
	while(oNode.tagName != "BODY" && oNode.tagName != "HTML") { // IE skips BODY?
		if (oNode.offsetLeft < 0)
			// IE6 is broken.. or something XXX 
			iLeft += 128;
		else
			iLeft += oNode.offsetLeft;
		oNode = oNode.offsetParent;		
	}
	
	return iLeft;
};

/**
 * Gets the top coordinate of the textbox.
 * @scope private
 * @return The top coordinate of the textbox in pixels.
 */
AutoSuggestControl.prototype.getTop = function () /*:int*/ {
	var oNode = this.textbox;
	var iTop = 0;
	
	while(oNode.tagName != "BODY" && oNode.tagName != "HTML") { // IE skips BODY?
		iTop += oNode.offsetTop;
		oNode = oNode.offsetParent;
	}
	
	return iTop;
};

/**
 * Highlights the next or previous suggestion in the dropdown and
 * places the suggestion into the textbox.
 * @param iDiff Either a positive or negative number indicating whether
 *			  to select the next or previous sugggestion, respectively.
 * @scope private
 */
AutoSuggestControl.prototype.goToSuggestion = function (iDiff /*:int*/) {
	var cSuggestionNodes = this.layer.childNodes;
	
	if (cSuggestionNodes.length > 0) {
		var oNode = null;
	
		if (iDiff > 0) {
			if (this.cur < cSuggestionNodes.length-1) {
				oNode = cSuggestionNodes[++this.cur];
			}		
		} else {
			if (this.cur > 0) {
				oNode = cSuggestionNodes[--this.cur];
			}	
		}
		
		if (oNode) {
			this.highlightSuggestion(oNode);
			this.textbox.value = oNode.firstChild.nodeValue;
		}
	}
};

/**
 * Handles three keydown events.
 * @scope private
 * @param oEvent The event object for the keydown event.
 */
AutoSuggestControl.prototype.handleKeyDown = function (oEvent /*:Event*/) {
	switch(oEvent.keyCode) {
		case 38: //up arrow
			this.goToSuggestion(-1);
			break;
		case 40: //down arrow 
			this.goToSuggestion(1);
			break;
		case 27: //esc
			this.textbox.value = this.userText;
			this.selectRange(this.userText.length, 0);
			/* falls through */
		case 13: //enter
			this.hideSuggestions();
			oEvent.returnValue = false;
			if (oEvent.preventDefault) {
				oEvent.preventDefault();
			}
			break;
	}
};

/**
 * Handles keyup events.
 * @scope private
 * @param oEvent The event object for the keyup event.
 */
AutoSuggestControl.prototype.handleKeyUp = function (oEvent /*:Event*/) {
	var iKeyCode = oEvent.keyCode;
	var oThis = this;
	
	//get the currently entered text
	this.userText = this.textbox.value;
	
	clearTimeout(this.timeoutId);

	//for backspace (8) and delete (46), shows suggestions without typeahead
	if (iKeyCode == 8 || iKeyCode == 46) {
		
		this.timeoutId = setTimeout( function () {
			oThis.provider.requestSuggestions(oThis, false);
		}, 250);
		
	//make sure not to interfere with non-character keys
	} else if (iKeyCode < 32 || (iKeyCode >= 33 && iKeyCode < 46) || (iKeyCode >= 112 && iKeyCode <= 123)) {
		//ignore
	} else {
		//request suggestions from the suggestion provider with typeahead
		this.timeoutId = setTimeout( function () {
			oThis.provider.requestSuggestions(oThis, true);
		}, 250);
	}
};

/**
 * Hides the suggestion dropdown.
 * @scope private
 */
AutoSuggestControl.prototype.hideSuggestions = function () {
	this.layer.style.visibility = "hidden";
};

/**
 * Highlights the given node in the suggestions dropdown.
 * @scope private
 * @param oSuggestionNode The node representing a suggestion in the dropdown.
 */
AutoSuggestControl.prototype.highlightSuggestion = function (oSuggestionNode) {
	
	for (var i=0; i < this.layer.childNodes.length; i++) {
		var oNode = this.layer.childNodes[i];
		if (oNode == oSuggestionNode) {
			oNode.className = "current"
		} else if (oNode.className == "current") {
			oNode.className = "";
		}
	}
};

/**
 * Initializes the textbox with event handlers for
 * auto suggest functionality.
 * @scope private
 */
AutoSuggestControl.prototype.init = function () {
	//save a reference to this object
	var oThis = this;

	//assign the onkeyup event handler
	this.textbox.onkeyup = function (oEvent) {
	
		//check for the proper location of the event object
		if (!oEvent) {
			oEvent = window.event;
		}	
		
		//call the handleKeyUp() method with the event object
		oThis.handleKeyUp(oEvent);
	};
	
	//assign onkeydown event handler
	this.textbox.onkeydown = function (oEvent) {

		//check for the proper location of the event object
		if (!oEvent) {
			oEvent = window.event;
		}	
		
		//call the handleKeyDown() method with the event object
		oThis.handleKeyDown(oEvent);
	};
	
	//assign onblur event handler (hides suggestions)	
	this.textbox.onblur = function () {
		oThis.hideSuggestions();
	};
	
	//create the suggestions dropdown
	this.createDropDown();
};

/**
 * Selects a range of text in the textbox.
 * @scope public
 * @param iStart The start index (base 0) of the selection.
 * @param iEnd The end index of the selection.
 */
AutoSuggestControl.prototype.selectRange = function (iStart /*:int*/, iEnd /*:int*/) {

	//use text ranges for Internet Explorer
	if (this.textbox.createTextRange) {
		var oRange = this.textbox.createTextRange(); 
		oRange.moveStart("character", iStart); 
		oRange.moveEnd("character", iEnd - this.textbox.value.length);	  
		oRange.select();
		
	//use setSelectionRange() for Mozilla
	} else if (this.textbox.setSelectionRange) {
		this.textbox.setSelectionRange(iStart, iEnd);
	}	 

	//set focus back to the textbox
	this.textbox.focus();	  
}; 

/**
 * Builds the suggestion layer contents, moves it into position,
 * and displays the layer.
 * @scope private
 * @param aSuggestions An array of suggestions for the control.
 */
AutoSuggestControl.prototype.showSuggestions = function (aSuggestions /*:Array*/) {
	var oDiv = null;
	this.layer.innerHTML = "";  //clear contents of the layer
	
	for (var i=0; i < aSuggestions.length; i++) {
		oDiv = document.createElement("div");
		oDiv.appendChild(document.createTextNode(aSuggestions[i]));
		this.layer.appendChild(oDiv);
	}
	
	this.layer.style.left = this.getLeft() + "px";
	this.layer.style.top = (this.getTop()+this.textbox.offsetHeight) + "px";
	this.layer.style.visibility = "visible";

};

/**
 * Inserts a suggestion into the textbox, highlighting the 
 * suggested part of the text.
 * @scope private
 * @param sSuggestion The suggestion for the textbox.
 */
AutoSuggestControl.prototype.typeAhead = function (sSuggestion /*:String*/) {
	//check for support of typeahead functionality
	if (this.textbox.createTextRange || this.textbox.setSelectionRange){
		var iLen = this.textbox.value.length; 
		this.textbox.value = sSuggestion; 
		this.selectRange(iLen, sSuggestion.length);
	}
};

/**
 * Provides suggestions for state/province names.
 * @class
 * @scope public
 */
function SuggestionProvider(suggestUrl, paramName, extraParams) {
	this.suggestUrl = suggestUrl;
	this.paramName = paramName;
	this.extraParams = extraParams || null;
}

/**
 * Request suggestions for the given autosuggest control. 
 * @scope protected
 * @param oAutoSuggestControl The autosuggest control to provide suggestions for.
 */
SuggestionProvider.prototype.requestSuggestions = function (oAutoSuggestControl /*:AutoSuggestControl*/,
															bTypeAhead /*:boolean*/) {
	suggest = function(response) {
			//evaluate the returned text JavaScript (an array)
			var aSuggestions = eval("(" + response + ")"); //JSON.parse(oHttp.responseText);
			//provide suggestions to the control
			oAutoSuggestControl.autosuggest(aSuggestions, bTypeAhead);		
	}

	var args = "?" + this.paramName + "=" + encodeURIComponent(oAutoSuggestControl.userText);
	if (this.extraParams != null)
		args += "&" + this.extraParams;

	ajaxRequest(this.suggestUrl + args, suggest);
};